The International Space Station Program and SpaceX have selected Friday for the next launch attempt of the Falcon 9 rocket to send the Dragon cargo craft on the company’s third commercial resupply mission to the station from the Cape Canaveral Air Force Station in Florida. NASA Television coverage of the 3:25 p.m. EDT launch begins at 2:15 p.m.
A launch Friday will send Dragon on a course to rendezvous with the station Sunday morning. Commander Koichi Wakata and Flight Engineer Rick Mastracchio will capture the space freighter using the Canadarm2 robotic arm at 7:14 a.m. to set it up for its berthing to the Earth-facing port of the Harmony module. Live NASA Television coverage of Sunday’s Dragon activities begins at 5:45 a.m. and returns at 9:30 a.m. for coverage of the berthing of Dragon to the Earth-facing port of the Harmony node.
If the Dragon space freighter launches Friday, a 2 ½-hour contingency spacewalk by Mastracchio and Flight Engineer Steve Swanson to replace a failed backup computer relay box in the station’s S0 truss will take place on Wednesday, April 23. A multiplexer demultiplexer backup computer relay system that assists in providing insight into truss systems, the operation of the external cooling loops, the operations of the Solar Alpha Rotary joints and the Mobile Transporter rail car failed on Friday, April 11, prompting the need for the contingency spacewalk.
If SpaceX scrubs the launch attempt Friday, the date of the contingency spacewalk moves earlier to Sunday. The U.S. Air Force 45th Weather Squadron forecast predicts a 40 percent chance of favorable weather for launch Friday. SpaceX has settled on a backup launch date of Saturday, April 19 for the best pair of launch dates for the science payloads being delivered to the station. If needed, a Saturday launch would occur at 3:02 p.m.
The Expedition 39 astronauts aboard the International Space Station focused much of their attention Wednesday on preparations for the spacewalk.
Swanson completed the checkout of the spacesuit that he will wear during the excursion. Mastracchio meanwhile checked out a pair of spacesuit “life jackets” known as the Simplified Aid For EVA Rescue, or SAFER. In the unlikely event a spacewalker became untethered during a spacewalk and begin floating away from the station, the small nitrogen-jet thrusters of SAFER would propel the astronaut back to safety.
The NASA astronauts also resized their spacesuits and gathered tools they will use during the excursion.
Wakata meanwhile configured two cameras that the spacewalkers will carry with them outside the station. The Japanese commander later cleaned up the Quest airlock by removing and stowing unneeded equipment to get the airlock ready for the upcoming spacewalk.
In addition to preparing for the upcoming spacewalk, Mastracchio and Wakata also supported ongoing research into the effects of long-duration spaceflight on the human body. Medical researchers have observed that astronauts grow up to three percent taller while living in microgravity and return to their normal height when back on Earth. The Spinal Ultrasound investigation seeks to understand the mechanism and impact of this change while advancing medical imaging technology by testing a smaller and more portable ultrasound device aboard the station. With remote guidance from the team on the ground, Wakata performed a spinal scan on Mastracchio.
On the Russian side of the complex, Flight Engineers Mikhail Tyurin and Alexander Skvortsov performed the Bar experiment, studying methods and instruments for detecting the location of an air leak from one of the station’s modules.
Afterward, Skvortsov teamed up with Flight Engineer Oleg Artemyev to continue unloading the ISS Progress 55 cargo ship, which delivered nearly three tons of cargo to the orbital laboratory when it launched and docked with the station’s Pirs docking compartment on April 9.
Artemyev later participated in the Interactions experiment, which studies the impacts of personal, cultural and national differences among crew members. He also worked with Vizir photography equipment, which is designed to automatically detect sites for Earth photography using ultrasonic angle measurement.
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